In addition to being the founding document of modern evolutionary biology, Darwin's magnum opus is also a perfect example of elegant, undeniable reasoning...and it is also beautifully written. This work is a both a philosophical and scientific masterpiece.

A great film, a true modern classic...but also filled with interesting philosophical questions about free will, perception, and truth (among others). Anyone hoping to dip their feet into "brain-in-a-vat" arguments about reality and perception would do well to watch and rewatch this movie.

This book changed not only the discourse on philosophy of science, but also the ways in which we think about developments in understanding and technology (if you've ever heard or used the word "paradigm," you can thank Kuhn). Essential reading for subsequent work in and understanding of philosophy of science.

Almost all of Western philosophy can trace its roots through to Aristotle and Plato. While much of this classic work is of primarily historical value, Aristotle's work on the nature of time, his moral philosophy, and numerous other subjects remain both relevant and engaging.

This survey work by one of the most prominent philosophers of the last hundred years covers the essentials of many different subjects, but it is most importantly a great way for beginners to access Russell's highly influential theories about truth and knowledge. This is a core work for understanding the logical advancements of analytic philosophy.

Virtually all of the most important works on meaning, language, metaphysics, and philosophical logic from the last century or so are either in this collection, or should first be accessed via these works.

Without a doubt, the most important work of political philosophy since the 1850s (and arguably longer). Rawls sets the stage for how contemporary political philosophers reason and talk about what justice means and how it relates to the role of the state.

On Liberty is one of the most powerful, insightful, and beautifully written pieces of philosophy ever, period: everyone who values democracy at its core should read this. The Subjection of Women is also one of the great early works on what would eventually become feminist philosophy.

Singer is probably the most influential and most controversial living ethicist, with important contributions across virtually all disciplines of moral philosophy. This work is aimed at lay people and explores the nature and extent of our obligation to help others.

A superb overview of both classic and contemporary issues in foundational epistemology. While intellectually challenging, much of this work remains accessible and rewarding even to amateurs with a serious interest in the problems of knowledge.